WASHINGTON - A bipartisan coalition of senators is working on a proposal to strengthen and expand background checks for potential gun purchasers in an attempt to break the partisan gridlock holding up regulations on gun ownership.

Members of the group, which includes Republicans Tom Coburn of Oklahoma and Mark Kirk of Illinois and Democrats Charles Schumer of New York and Joe Manchin of West Virginia, have declined to discuss specifics of the talks or of a potential bill.

Coburn spelled out what he wants in any bill.

Laws, he said, need to be updated to ensure that guns stay out of the hands of "people that are a danger to themselves and other people.

"I believe the mentally ill should never be able to get a gun, I believe criminals should never be able to get a gun," he said. "There's nothing wrong with updating what we're doing to try to make that more effective."

The nation must improve the system to encourage states to report the mentally ill and install protections for doctors to enable them to report patients who are "obviously psychotic" to prohibit them from buying guns, Coburn said.

Manchin said the senators "are just talking to everybody, that's all. Everybody's just trying to work together to find ... some common-sense movement, if you will."

Last weekend, Manchin told a West Virginia radio station he was working with Democratic and Republican senators, as well as the National Rifle Association, on something gun rights supporters could back. Such a bill, Manchin said, "basically says that if you're going to be a gun owner, you should be able to pass a background check."

Schumer called universal background checks "the sweet spot" and predicted bipartisan support on the issue during an appearance Jan. 20 on NBC's Meet the Press.

"I think you're going to see ... in the next week or two a proposal that has broad support for universal background checks. ... This is the best chance of getting something done," Schumer said. " And I think you're going to find much broader support than we ever imagined."

Sen. Richard Blumenthal, D-Conn., introduced his own background check proposal Tuesday that focuses on the sale of ammunition. He said he has spoken to Schumer about the bipartisan background check bill often and would support it.

Through the National Instant Criminal Background Check System, more than 100 million background checks have been made in the past 10 years, according to the FBI website. The checks led to more than 700,000 denials. Gun-control activists are quick to note that guns bought at gun shows, on the Internet or at private sales are not subject to the same requirements, creating a "loophole" for those who want to avoid background checks.

There are signs from the White House that it would support a background check proposal. Vice President Biden specifically advocated universal background checks during an appearance in Richmond last week to promote President Obama's gun regulation proposals.

Biden said the proposal "in no way impacts upon someone's ability under the Constitution to own a gun."

As the momentum around background checks appears to be building, the support for an assault weapons ban, introduced last week by Sen. Dianne Feinstein, D-Calif., seems to have stagnated.

"She's talked to me about her assault weapons ban, a new one," he said. "I'll take a look at that. As I've indicated to you folks, we're going to have votes on all kinds of issues dealing with guns. ... And I think everyone would be well-advised to read the legislation before they determine how they're going to vote for it."

These proposals and others will be among those discussed Wednesday during a Senate Judiciary Committee hearing, which will be the Senate's first such forum on gun violence in this Congress.

That committee, chaired by Sen. Patrick Leahy, D-Vt., will feature testimony from astronaut Mark Kelly, the husband of gunshot victim and former representative Gabrielle Giffords, and NRA Executive Vice President Wayne LaPierre. Giffords and Kelly have created a political organization to promote gun regulations.

In a statement released by the NRA on Tuesday, LaPierre said he will express opposition to universal background checks during the hearing but said moves should be made to strengthen checks related to the mentally ill.

"And when it comes to the issue of background checks, let's be honest: Background checks will never be 'universal,' because criminals will never submit to them," LaPierre said in the statement.